Exciting light emission and ultrasonic temperature measurement

Exciting light emission and ultrasonic temperature measurement

Glowing substance during an experiment at the University of Jena. Credit: Jens Meyer/University of Jena

If materials with mechanical luster are subjected to external mechanical stress, they emit visible or invisible light. Such excitation can be caused by bending or gentle pressure, for example, but also completely contactless by ultrasound. In this way, the effect can be triggered remotely and the light can be brought to places that would normally be in the dark, for example in the human body. If ultrasound therapy is to be used at the same time to generate local heat, it is important in such a sensitive environment to closely monitor the occurring temperatures. Materials scientists at Friedrich Schiller University Jena in Germany have now developed a mechanically irradiated material that can not only be used to generate local heat inputs via ultrasound, but also provides local temperature feedback at the same time. They report their findings today in the journal advanced science.

Semiconductors and rare earths

Jenna scientists in their work often deal with the mechanical properties of inorganic materials, in particular how one can visually observe mechanical processes.

mechanically induced light emission It can provide us with many details about the response of a material to mechanical stress,” explains Professor Lothar Wondrashek from the University of Jena. But in order to expand the field of applications, it is sometimes necessary to obtain additional information about the local temperature – especially when excitation by ultrasound is performed. Here, we were initially interested in sensing materials in the form of ultrafine particles, which – introduced into the environment to be studied – can provide feedback on how ultrasound interacts with this environment. ”

For this purpose, the Jena researchers combined an oxy-sulfide semiconductor with rare-earth erbium oxide. The mechanical energy provided by ultrasonic excitation is absorbed by the semiconductor structure, with erbium oxide providing the light emission. The temperature can then be read from the spectrum of light emitted by optical thermometry.

“This means that we can stimulate a temperature increase From the outside, measure it from the light-emitting characteristics, thus creating a complete control circuit,” explains Wondraczek.

Application in photodynamic therapy

Remote light emission, combined with temperature control, could open up entirely new areas for the application of such mechanically lit materials, for example in medicine. “It could be one of the possible areas of application Phototherapywhere light is used to control photophysical processes that can support the organism in healing,” says materials scientist Wondrashek.

With multi-response materials in a very mechanical sparkle shape fine particles, not only can generate light and heat at the desired location, but can also be controlled in a targeted manner. as such biological tissue transparent to infrared light emitted, it is possible to set the desired temperature and control it from the outside during processing. “However, such ideas are still in their infancy. Very extensive research and study are still required in order to put them into practice.”

Other applications where light and heat must be brought into dark places are more easily accessible in a targeted manner. For example, photosynthesis or other light-driven reactions can be specifically triggered, monitored, and controlled. Likewise, going back to the beginning, the material can be used as a sensor to generate or notice physical changes, or also as an invisible and encoded marker on material surfaces.

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more information:
Yicong Ding et al, Ultrasound, induced mechanical luminescence and optical thermometry toward stimulus, responsive subjects with simultaneous trigger response and reading functions, advanced science (2022). DOI: 10.1002 / advs.202201631

the quote: Exciting Light Emission and Ultrasound Temperature Measurement (2022, June 17) Retrieved on June 19, 2022 from https://phys.org/news/2022-06-emission-temperature-ultrasound.html

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